There's one senator among this bipartisan working group who is seen as critical to getting this deal through both chambers

"I do like the things that Marco Rubio has been laying out," Sen. Bob Corker (R-TN) said on "Fox News Sunday".

Florida Senator Marco Rubio is a Tea Party favorite and a potential presidential candidate in 2016. Many here say he's key to getting conservatives to support the bill.

"I support and agree with the principals that he laid out about earned legalization. Making sure you're not rewarding people who cut in line, but making sure that we can fix this problem," Rep. Paul Ryan (R-WI), said on NBC's "Meet the Press".

And then there's the political calculus. Some Republicans say they need this bill to win over Hispanic voters.

"Look at the last election. We are losing, dramatically, the Hispanic vote, which we think should be ours for a variety of reasons, and we've got to understand that," McCain said.

Hispanics supported President Obama over Mitt Romney with more than 70-percent of the vote.

President Obama will talk about immigration reform tomorrow at a speech in Nevada.